South African President Nelson Mandela celebrated his 80th birthday on Saturday by exchanging diamond-studded wedding rings with Graca Machel, the woman he has long insisted be treated as South Africa's first lady.

Mandela and his longtime sweetheart, 52, the widow of Mozambican President Samora Machel, wed in a private ceremony at the president's house in the exclusive Johannesburg suburb of Houghton.

They exchanged rings and a lingering kiss during the ceremony performed by a Methodist minister and with blessings from Jewish, Hindu and Muslim religious leaders.

Charting his comeback

Tom Arnold wants to start getting picky.

After box-office flops like The Stupids and Big Bully, Roseanne's ex-husband says it's time to get more selective, so he hired a new manager. "My goal, obviously, is to get to the point where I can pick up some supporting roles in movies, and maybe star in some movies, but not the stuff I've been doing," he said Friday at the Tom Arnold Summer Theater Workshop in Ottumwa, Iowa. "I was ruining my movie career by doing too many bad movies."

His advice to the aspiring actors was to start slowly and get as much experience as possible in local theaters before setting out for the big cities _ and don't let the flops get you down.

"All the big stars have bombs," he said.

ALMANAC

It's the 200th day of the year; 165 days are left in 1998. On this day:

* In 1553, Lady Jane Grey, 15, was deposed as queen of England after claiming the crown for nine days. King Henry VIII's daughter Mary was proclaimed queen.

* In 1848, a women's-rights convention called by Elizabeth Cady Stanton and Lucretia C. Mott opened in Seneca Falls, N.Y.

* In 1989, 112 people were killed when a United Air Lines DC-10 crashed while making an emergency landing at Sioux City, Iowa; 184 other people survived.

Thought for today: "No written law has ever been more binding than unwritten custom supported by popular opinion." _ Feminist